New Trends in the Chemistry of Inorganic Polymers for Advanced Applications

MacKenzie, Kenneth J.D.; Komphanchai, Suwitcha; Fletcher, Ross A.

doi:10.1002/9780470339749.ch23

Cited by 4 publications

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“…Inorganic polymers (IP) are relatively new materials that can be used in construction, but more advanced applications are also being explored, such as use in bioactive materials, electronic materials, for example . The impetus behind the renewed interest in IPs relates to the need to find alternative cementitious binders with an overall lower environmental footprint .…”

Section: Introductionmentioning

confidence: 99%

Kinetics of pore formation and resulting properties of lightweight inorganic polymers

2019

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Inorganic polymer (IP) foams could be used as an alternative to commonly available cellular concretes. To do so, however, it is crucial to understand how the foaming kinetics and the final foam properties can be controlled and tailored to delivered the desired performance. The research reported in this article investigates the influence of the SiO 2 /Na 2 O ratio of the activating solution, addition time of foaming agent, and temperature, on the reaction kinetics and final properties of a porous IP. The IPs were formed by activating fayalite slag, a by-product of secondary copper production, with a sodium-silicate solution. Foaming was achieved by introducing metallic Al into the formulation, oxidizing it in the alkaline environment, liberating H 2 gas, and entrapping it. Reaction kinetics were assessed using isothermal calorimetry, rheology, and a dedicated setup to record the foaming. The mechanical and physical properties of the foam were assessed via compressive strength and water absorption measurements. Microstructural analysis was undertaken using electron microscopy and computed tomography. The results showed that by decreasing the SiO 2 /Na 2 O ratio and/or increasing the temperature, the reaction kinetics were accelerated. Regarding the properties, postponing the initiation of the foaming led to more uniform and smaller pores, resulting in an increased compressive strength-to-density ratio. K E Y W O R D Sinorganic polymers, kinetics, pore formation, porous materials

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Section: Introductionmentioning

confidence: 99%

Kinetics of pore formation and resulting properties of lightweight inorganic polymers

2019

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“…Kenneth MacKenzie (supervisor of this work) [22]. By combining the good mechanical properties of inorganic polymers with the bioactive behaviour of substances such as calcium hydroxide, nano structured calcium silicate and calcium phosphate, we can develop a durable implant.…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

“…In contrast to previous experiments carried out by Oudadesse [3,11] and Martin [4], this work aims to create an in-situ geopolymer containing calcium and possibly phosphorus, synthesised in a one-step process rather than in two or more steps. It has been reported that calcium and phosphorus can be successfully incorporated in inorganic polymers without disturbing the typical properties of a true geopolymer (producing an amorphous network structure as well as aluminium and silicon in tetrahedral sites) [22] [23].…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

“…43 Ca MAS NMR studies have been carried out on these compounds [24]. The calcium phosphate geopolymer develops HCA precursors after 1 and 7 days exposure to SBF [22].…”

Section: Chapter 2 Literature Reviewmentioning

confidence: 99%

“…To prepare geopolymers that set and harden, attention must be paid to the ratios of Al : Si, K : Si and H 2 O : K 2 O. A geopolymer formulation which had been successfully used for previous in-vitro studies was used as a basis [22]. This material was reproduced, then the amount of alkaline compounds was progressively reduced to a minimum to produce a material with low alkalinity.…”

Section: Sample Formulationmentioning

confidence: 99%

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Inorganic Polymers (Geopolymers) as Potential Bioactive Materials

Rahner¹

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<p>The primary aim of this project was to synthesise potassium activated geopolymer composites with bioactivity, and this was realised by adding 10wt% of calcium hydroxide, nano-structured calcium silicate or calcium phosphate to the geopolymer matrix. The synthesised samples were cured at 40'C then heated to 550'C and 600'C to reduce their alkalinity. Tensile strength was measured by diametral compression. The effect of exposure to simulated body fluid (SBF) was determined by x-ray diffractometry (XRD), 27Al, 29Si and 43Ca nuclear magnetic resonance spectroscopy with magic angle spinning (MAS NMR), pH measurements, inductively coupled plasma (ICP), scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDS). XRD, 27Al and 29Si MAS NMR confirmed that all the samples retained their structural characteristics of a true aluminosilicate geopolymer, even after heating and exposure to SBF. EDS examination of the calcium-containing geopolymer composites showed that the calcium distribution was generally homogeneous. Exposure of the geopolymer composites to SBF at body temperature, was used to simulate the behaviour of the geopolymer composites in blood plasma. XRD and SEM/ EDS analysis showed that the geopolymers containing calcium hydroxide and calcium silicate formed hydroxyl apatite (HA) and carbonate hydroxyl apatite (HCA) after their exposure to SBF, indicating a degree of bioactivity. The absorption of calcium and phosphorus from the SBF and the observation of nano crystals rich in these elements provide some evidence of bioactive phases in the composite containing calcium phosphate and the reference geopolymer. The reference and the calcium phosphate geopolymer (both heated to 600XC) produced the lowest pH (ca.8) in the SBF. ICP analysis of the SBF after exposure shows that most of the aluminium remains in the geopolymer structure. The greatest release of aluminium (< 2.7 ppm after 168 hours) was found for the calcium hydroxide geopolymer (heated to 600'C). Diametral compression testing showed that the strength of the calcium phosphate-containing geopolymer heated to 550'C (4.17 MPa) is comparable with that of Bioglass(R)(5.56 MPa), currently used as a bio-material. Although none of the composites are ideal in all respects, they show sufficient promise to suggest that with further refinement, geopolymer materials may well be become candidates as bioactive ceramics.</p>

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Structural elucidation of synthetic calcium silicates

et al. 2008

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A series of synthetic calcium silicates has been produced comprising nano-sized plates. The starting calcium silicate referred to as nano-structured calcium silicate, NCS, appears itself X-ray amorphous but contains impurities of calcite. These impurities decompose during the dry thermal conversion of the material into wollastonite. NCS can be enriched with calcium or silicon, respectively. The silicon enriched NCS can be hydrothermally transformed into a sheet material related to Ca7Si16O38(OH)2. The X-ray pattern of this material was sufficient to allow the calculation of its unit cell with a comparatively high figure of merit. The calcium enriched NCS can form two very distinctly different ceramic materials upon hydrothermal treatment, one a band material (formed below 200 °C) and the other a rose petal shaped material (formed above 210 °C). The X-ray diffraction patterns could not be resolved. The fit between the observed and calculated patterns was less than 50% as expressed in comparatively low figures of merit (unusually <20), which is attributed to calcium carbonate impurities in the samples disrupting the long range order. The patterns of these calcium enriched samples could be best compared to those of tobermorite or truscotite.

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New Trends in the Chemistry of Inorganic Polymers for Advanced Applications

Cited by 4 publications

References 0 publications

Kinetics of pore formation and resulting properties of lightweight inorganic polymers

Kinetics of pore formation and resulting properties of lightweight inorganic polymers

Inorganic Polymers (Geopolymers) as Potential Bioactive Materials

Structural elucidation of synthetic calcium silicates

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